Connection element

ABSTRACT

A connection element for connecting two parts, in particular, an external component with a vacuum pump, includes a first member engageable with the external component, and a second member engageable with the connection component provided on the pump housing, with the first and second members being slidable relative to each other during connection of the external component with the vacuum pump and having slidable relative to each other surfaces having a predetermined and unchangeable frictional resistance.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to a connection elements, e.g., a clamp, for connecting two parts and, in particular for connecting an external component with a vacuum pump including a high-speed rotor and stationary and rotatable components arranged in a pump housing having a connection component, with the connection element including a first member engageable with the external component, and a second member engageable with the connection component provided on the pump housing, and with the first and second members being slidable relative to each other during connection of the external component with the vacuum pump.

2. Description of the Prior Art

Vacuum pumps with a high-speed rotor, such as, e.g., turbomolecular pumps, store in the rotor, because of its high speed, a large amount of energy. Upon rotor/stator crash, this energy is transmitted over stationary components, such as, e.g., a connection flange or bottom parts, to other components of an installation. The generated torque can cause damage or destroy the parts of the installation which are connected with the vacuum pump. The generated torque can cause the tearing of the pump off, its rotation on the installation, or the tearing off of the connection elements of the pump which is dangerous for the personnel.

In the vacuum installation, usually, during a crash, leakage takes place. The leakage adversely affects the conducted process and, therefore, the process should be interrupted. Moreover, if toxic gases are involved, the leakage leads to contamination of the environment.

Conventionally, the connections between the vacuum pumps and, e.g., an installation is effected with clamps. They are tightened with locking bolts, which results in preload of the connected parts. The preload plays a crucial role in a torsional resistance of the components. It depends in a significant manner on the frictional resistance of threaded connections and of contact parts of the clamp. The frictional resistance itself depends from a respective material pairing and from condition of contacting each other surfaces. In addition, with a repeated assembly, because of wear, the helical thread can become blocked, or the clamp members can become blocked. The preload reduces, with repeated assembly and disassembly, the constancy of the tightening torque.

Accordingly, an object of the present invention is to provide a connection element, in particular for vacuum pumps with a high-speed rotor, and which would insure a reliable connection of the vacuum pump, e.g., with an installation, e.g., for bottom connection or for connection of pump parts arranged beneath one another.

Another object of the present invention is to provide a connection element for vacuum pumps with a high-speed rotor and which would prevent any serious damage upon a rotor/stator crash.

SUMMARY OF THE INVENTION

These and other objects of the present invention, which will become apparent hereinafter, are achieved by providing a connection element in which the slidable relative to each other surfaces have a predetermined and unchangeable frictional resistance.

Because of the predetermined and unchangeable frictional resistance of the sliding, relative to each other, surfaces, even with a repeated assembly, the preload remains constant. Thereby, the connection of the vacuum pump with an external component, with bottom connections, or between separate sections of stationary components, is substantially more reliable than with conventional means. Serious damages, upon a rotor/stator crash, are prevented.

The novel features of the present invention, which are considered as characteristics for the invention, are set forth in the appended claims. The invention itself, however, both as to its construction and its mode of operation, together with additional advantages and objects thereof, will be best understood from the following detailed description of a preferred embodiment, when read with reference to the accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

In the Drawings:

Single FIGURE shows a cross-sectional view of a locking bolt according to the present invention for a vacuum pump with a high-speed rotor.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT

In the drawing, there is shown a preferred embodiment of a connection element according to the present invention by way of a clamp. A first member 1 of the clamp, which is provided with a groove 2 and which engages a part 7 (e.g., of a vacuum installation), slides in a second member 3 of the clamp. The second member 3 is likewise provided with a groove, groove 4, which engages a flange of a vacuum pump 8. The lower end of the clamp member 1 is provided with a thread 6 that cooperates with a nut 5 for locking both members 1 and 3 together. At a location 9, the surfaces of the clamp members 1 and 3 slide relative to each other. The surfaces of the thread 6 and of the clamp members at a location 9 have a predetermined and unchangeable frictional resistance. This can be achieved by a proper selection of materials or by providing the surfaces of the involved components with an appropriate coating, respectively. The material used for the manufacturing of respective components can be the same or different. A portion of the surfaces or all of the surfaces can be provided with a coating with integrated lubrication means.

Though the present invention was shown and described with references to the preferred embodiment, such is merely illustrative of the present invention and is not to be construed as a limitation thereof and various modifications of the present invention will be apparent to those skilled in the art. It is therefore not intended that the present invention be limited to the disclosed embodiment or details thereof, and the present invention includes all variations and/or alternative embodiments within the spirit and scope of the present invention as defined by the appended claims. 

1. A connection element for connecting an external component with a vacuum pump including a high-speed rotor and stationary and rotatable components arranged in the pump housing having a connection component, the connection element comprising a first member engageable with the external component; and a second member engageable with the connection component provided on the pump housing, the first and second members being slidable relative to each other during connection of the external component with the vacuum pump and having slidable relative to each other surfaces having a predetermined and unchangeable frictional resistance.
 2. A connection element as set forth in claim 1, wherein the slideable relative to each other surfaces of the first and second members are provided with a coating having a predetermined and unchangeable frictional resistance.
 3. A connection element as set forth in claim 1, wherein the first and second members are formed of materials surfaces of which have a predetermined and unchangeable frictional resistance.
 4. A connection element as set forth in claim 3, wherein the first and second members are formed of different materials the surfaces of which have, in cooperation with each other, a predetermined and unchangeable frictional resistance.
 5. A connection element as set forth in claim 1, wherein the connection element is formed as a clamp.
 6. A connection element as set forth in claim 2, wherein the coating includes integrated lubrication means.
 7. A clamp for connecting two parts having respective connection components, the clamp comprising a first member engageable with a connection component of one of the two parts; a second member engageable with a connection component of another of the two parts, the first and second members being slidable relative to each other during the connection of the two parts and having slidable relative to each other surfaces having a predetermined and unchangeable frictional resistance; and means for connecting the first and second members together.
 8. A clamp as set forth in claim 7, wherein the respective connection components of the two parts are formed as projections extending in opposite directions, and the first and second members have respective grooves in which the respective connection components engage upon connection of the two parts.
 9. A clamp as set forth in claim 7, wherein the first member is formed as a clamp bolt provided at a free end thereof with a thread, and the second member has an opening through which the free end of the clamp bolt is extendable, and wherein the connecting means comprises a nut that is screwed on the thread for connecting the first and second members of the clamp together.
 10. A clamp as set forth in claim 7, wherein the slidable relative to each other surfaces of the first and second members are provided with a coating having a predetermined and unchangeable frictional resistance.
 11. A clamp as set forth in claim 7, wherein the first and second members are formed of materials surfaces of which have a predetermined and unchangeable frictional resistance.
 12. A clamp as set forth in claim 11, wherein the first and second members are formed of different materials the surfaces of which have, in cooperation with each other, a predetermined and unchangeable frictional resistance. 